Surgical treatment of clubfoot: a comparison of two techniques.

Between 1977 and 1989, 28 clubfeet were operated on, with follow-up ranging from 2 to 13 1/2 years and averaging 79 months. Group I (16 feet; average follow-up 104 months) underwent a modified Turco's posteromedial release. The functional result in this group was satisfactory in general, but approximately one third of this group required a secondary procedure for persistent intoeing or residual metatarsus adductus. Group II (12 feet; average follow-up 45 months) underwent a modified, complete subtalar release of McKay and Simons utilizing the Cincinnati incision. No patient in this second group required a secondary procedure. In our experience, the more complete subtalar release procedure of McKay and Simons resulted in better correction than the Turco posteromedial release. Although follow-up in group II was much shorter than that in group I, we felt that 2 years of minimum follow-up in group II was meaningful, since most of the recurrence or residual deformities were noticed within 18 months after surgery. The Cincinnati incision allowed better exposure and a more complete release. Skin flap necrosis was not a problem in this series.

Inoperable endobronchial obstructing lung carcinoma treated with combined endobronchial and external beam irradiation.

Thirty patients with symptomatic inoperable endobronchial obstructing lung cancer received combined external beam radiotherapy and temporary endobronchial iridium Ir 192 implants. External beam irradiation doses ranged from 5700 to 6600 cGy. Patients were given two to four temporary iridium Ir 192 implants for endobronchial radiotherapy. Individual implant doses ranged from 500 to 1500 cGy. Total implant doses ranged from 1125 to 3000 cGy. Total treatment doses ranged from 7080 cGy to 10,000 cGy. Seventy-seven percent of patients had a complete local endobronchial response to treatment, and 13% had a partial response. Ninety percent of patients experienced an improvement in their performance status using an Eastern Cooperative Oncology Group (ECOG) scale. Survival from the end of treatment was 39% at 1 year and 21% at 2 years, with the median survival at 10 months. The data from this study indicate that this form of treatment of inoperable endobronchial obstructing lung cancer is feasible and leads to a high percentage of local tumor response, improvement in patient performance status, and possibly improved survival.

Pulmonary masses: contrast enhancement.

Radiographic studies to discriminate benign from malignant pulmonary masses have previously focused on the morphologic and, more recently, the computed tomographic (CT) attenuation characteristics of the lung mass. Experience with the use of an intravenously administered iodinated contrast medium in examining the enhancement properties of lung masses was reviewed. Distinctive differences in the vascularity, pathophysiologic features, and pharmacodynamics of malignant versus benign pulmonary masses were identified. Forty-five patients with peripheral pulmonary masses were examined. Enhancement was evaluated by means of optical density values measured on trispiral tomograms of the lung masses before and after bolus injection of contrast medium. Results suggest that contrast enhancement of pulmonary masses can be measured on sectional images and that this may become a feasible diagnostic method in the detection of lung cancer. CT offers a simplified technique that is now being explored by the authors.

The perceived clinical value of NMR measurements on biopsy specimens. Part I. Interval estimates of diagnostic error rates and a note on an effect of the law of small numbers.

There are currently two conflicting views concerning the value of NMR measurements (in vivo and in vitro) of the proton T1 and T2 relaxation times in tissues, in discriminating between normal (Ca) and malignant (Ca) conditions. Damadian repeatedly asserted that a linear combination of these two measurements, the so-called malignancy index, can, "...discriminate between normal and cancer tissue on a case-by-case basis...considerably better than 90%" and thus "...the technique is now ready for use by pathologists as an adjunct to present methods of diagnosing malignancy." On the other hand, Hollis countered that, "Neither nmr nor any other method requiring surgical biopsy is likely to replace or even supplement the standard histopathological techniques." Part I of the present paper examines the relation between the first of these two views and the sample data presented in their support. Part I is a "cautionary tale" in which the procedures used by Koutcher to obtain point estimates of the misclassification rates from these data are shown to be incorrect. (These procedures are identical to those used two decades earlier by Ternberg in an advocacy of the diagnostic use of EPR measurements on biopsied tissues.) It is also shown that the interval estimates of the misclassification rates obtained from these data, which have not previously been reported, are large enough to embrace both views; these data are "user-friendly"--a characteristic of small samples. It is shown that, in accordance with the Tversky-Kahneman (1971) Law of Small Numbers, the disparity in the two views can be accounted for by, "...underestimates of the breadth of confidence intervals" (due to the small sample sizes) by each group. The appropriate statistical procedures for determining point and interval estimates of such misclassification rates are also described and illustrated with the Koutcher, data. Part II describes a Discriminant Analysis of these data. It is, of course, still possible that proton T1 and T2 measurements can be used to reliably distinguish between normal and malignant tissues since absence of evidence is not always evidence of absence for an effect.

An extreme value paradigm for the effect of size of target volume on end results in radiation oncology.

In clinical radiation oncology, it is commonly reported that complications of normal tissue occur more readily at larger field sizes for a given dose and recurrence of disease is observed more frequently from the larger tumors for a given dose. Cognate phenomena have long been observed in the study of the strength of materials. That is, the larger specimens will fracture under less applied stress, breakdown under less applied voltage, corrode in a shorter time, etc. The statistical theory of extreme values has provided both a rational explanation and a technique for exploitation of these "size effects" on the likelihood of specimen failure. This theory describes the relation which exists between the parameters (in particular, the location parameter) of the frequency distributions of the extreme values [smallest x(1) and largest x(n)] in a sample from a population of observations xi and the sample size n. It is shown in the present paper that the clinical failure phenomena are not inconsistent with the statistical theory of extreme values. The paper presents heuristic comparisons of the predictions of this theory with the received clinical observations of the effect of the size of the volume of irradiated tissues on the likelihood of occurrence of the misadventures of clinical radiation oncology: recurrence of disease and complication of normal tissue. The concordance of observations and predictions is acceptable. The quality and quantity of the currently available data have precluded the construction of any apodictic representations.

"Battered data"--some clinical effects of the abuse of multiple regression methods: the NSD.

The NSD equation, D = 1850 x T0.11 x N0.24, is a celebrated transmogrification of Cohen's two well-known collations of data on response to clinical irradiations (3 degrees erythema and 0.90 ablation of skin cancer) in which the relation of D and T is fixed by the data selected by Cohen and the additional constraint that N correspond to a schedule of five treatments per week is imposed subsequently by Ellis. The present paper shows that the equation, if correct, would have little clinical significance because the proportion, P, in which the dose, D, elicits the 3 degree erythema is unspecified: D = D(P) = D(?). Since the two Cohen collations each summarize the measurements on a different set of observational units, it is questionable whether the equation can be correct. This paper further shows that the appropriate (Least Squares) estimates of the three-parameter equation derived for the Cohen data under the Ellis constraint (five treatments per week) is in fact: D(1.0) = 1710 x T0.54 x N-0.26. The paper shows that the NSD equation is also incorrect because the ad hoc method by which Ellis estimates the exponents is inconsistent with the constraints imposed by Cohen and Ellis upon the parameters of the multivariate frequency distribution of the data set. The paper shows that the method by which the correct LS estimates of the exponents were obtained from the Cohen-Ellis data is consistent with these constraints and, therefore, this equation is a correct graduation of any other set of treatment regimens which is also consistent with the Cohen and Ellis constraints. The paper further shows that for such data sets there are, in fact, only two independent continuous variables, either D and T or D and N, since the Ellis constraint requires that N and T be collinear. Thus, the best linear graduation has the typical form: D congruent to 1900T0.32. This is "best" in the usual sense: both prediction and confidence intervals are provided for the estimates of the conditional "tolerance dose" D; these are not inflated by the presence of a collinear variable. This equation is biased, however, by the absence of the collinear variable. The TDF and the CRE concepts are derived from the NSD and, therefore, the deficiencies of the latter concept which we discuss may be expected to encumber these progeny as well. The two characteristic features of the Cohen (Ellis)-type data which impede the construction of useful estimates of the putative separate effects of N and T upon the response of tissues to irradiation are that (1) these data do not include specifications of either a tissue defect or its incidence, and (2) the variables N and T are collinear. Appendices I and II describe methods by which the effects of these features may be eliminated (I) or reduced (II).

"Battered data"--some clinical effects of the abuse of multiple regression methods: a second look at some observations on Ro07-0582 (Misonidazole).

The paper presents an argument for the wider use of simple and standard statistical methods in the design and evaluation of both laboratory and clinical experiments with toxic radiosensitizers. It also presents an argument against the frequent practice of superposing a curve estimated from laboratory observations upon scattergrams of clinical observations to thereby assist the reader to the (often fallacious) inference that the two disparate sets of observations have enough in common to be graduated by the same curve. Such a practice achieves a substitution of reasoning by analogy for the more reliable statistical procedures of estimation and of testing a hypothesis.